Food products are often packaged in molded trays having a hinged or folded lid, manufactured from pulp material. Such products may be made from paper sheet plate stock, and are used as a vessel for storage and service of side dishes, frozen foods, and the like.
Generally speaking, when food products are placed in such trays and displayed for subsequent purchase, the paper trays are wrapped in a plastic wrap (such as polypropelene) so that the food contents can be observed visually prior to purchase. Such trays with paper lids may be used to store food products in a manner wherein the food is not visible. As illustrated in FIG. 4a ("Prior Art"), a molded tray 1' is comprised of a storage section 2' and a lid portion 3', and is provided with a hinge section 5' interconnecting the storage and lid sections. Often times the hinge section 5' is cut in on either side 6' to provide a reduced section that must be folded over. When the lid 3' is folded over (in the direction of arrow 7') to the position indicated by phantom lines in FIG. 4a, the hinge section 5' (which is merely a web portion of the lid and storage sections) is bent linearly along its length between the cut-in sections 6'.
When the hinge section 5' of prior art devices is not bent properly, the integrity of food stored therein is compromised. Food may spill out, or be exposed to an undesirable amount of ambient air, causing deterioration in food quality. Moreover, if the hinge section 5' is bent insufficiently, the lid 3' may exhibit a spring action, and be subject to returning to its original (open) position. Therefore, it is often necessary to perform the bending action a number of times (FIG. 4b) and then securely overlap the lid and storage portions in several spots to assure closure, resulting in excess time being spent in the packaging of the food product.
Some of the disadvantages noted above can be solved by providing a bending section 8' having a reduced thickness when compared with the remainder of the tray. For example, as illustrated in FIG. 4c, the bending section 8' may be provided by impressing or embossing a transverse area about which the lid 3' may rotate. Such an additional step necessarily adds both complexity and cost to the finished price of the product. Furthermore, when provided as illustrated in FIG. 4c, the "memory" of the lid section tends to create a spring-action which prevents the lid from lying adjacent the storage section in a closed position of its own weight. Accordingly, the device must be provided with closure means to maintain the lid closed, further adding to the cost and complexity of the device.
The process and product of the present invention is intended to resolve these and other problems by providing a process for the manufacture of a novel tray/lid combination wherein the lid can be bent easily and thereafter remain securely in the "closed" condition.